Vitamin D supplements ‘have no effect’ on depressive symptoms

Treating vitamin D deficiency does not reduce symptoms of
depression, according to a
Norwegian study published online today by the British
Journal of Psychiatry.

Some previous studies have found an
association between low vitamin D levels and depression, leading to
suggestions that vitamin D supplementation could help alleviate
symptoms.

Researchers from the University Hospital of
North Norway carried out a randomised placebo-controlled study to
examine whether supplementation works. They recruited 334 healthy
volunteers, of whom 230 had low vitamin D levels and 114 had high
vitamin D levels. All participants were assessed to determine if
they had depressive symptoms.

Those people with low vitamin D levels were
randomly split into two groups. One group received high dose
vitamin D supplementation for 6 months, the other received a
placebo. The 114 people with high vitamin D levels were given no
treatment and acted as a control group.

At the beginning of the study, the researchers found that
participants with low vitamin D levels were more depressed than
those with high levels. However, by the end of the 6 month study,
there was no difference in depression scores between those who had
taken the high dose vitamin D supplements and those who had taken
the placebo.

Lead researcher Dr Marie Kjærgaard said: "Our
randomised placebo-controlled study found that even though people
with low levels of vitamin D are more depressed, high dose vitamin
D supplementation had no effect. This may indicate that low levels
of vitamin D are the result – rather than the cause – of depressive
symptoms. Further studies are now needed in people with clinical
depression."